1. Field of the Invention
The present invention is generally in the field of electronic circuits and systems. More specifically, the present invention is in the field of communications circuits and systems.
2. Background Art
Transceivers are typically used in communications systems to support both transmission and reception of communication signals through a common antenna, for example, at radio frequency (RF) in a cellular telephone or other mobile communications to device. A conventional receiver implemented as part of a transceiver typically utilizes several stages to amplify and process a receive signal in a predetermined RF reception frequency range. In the receiver “front-end,” for example, a low noise amplifier (LNA) may be used to boost the receive signal prior to down-conversion from RF to baseband by a mixer stage. In a conventional receiver “back-end,” the baseband signal is then filtered by a high-order low-pass filter (LPF) providing substantial additional gain control in the conventional receiver design. Moreover, a transmitter implemented in such a conventional transceiver typically utilizes several processing stages configured using an open-loop design to condition and preamplify a transmit signal prior to passing the transmit signal to a power amplifier (PA).
As consumer demand for ever smaller, more powerful, and more inexpensive mobile communications devices increases, strategies are continuously being sought to make transceiver production less costly and more efficient. Traditionally, those strategies have focused primarily on increasing circuit integration and other approaches that reduce the physical measurables characterizing the transmitter and/or receiver implemented in the transceiver system. However, in addition to layout and dimensional factors, another source of cost in transceiver fabrication flows from conventional approaches to performing system testing and calibration. For example, conventional factory testing and calibration of a transceiver, that is to say factory testing and calibration of each of the transmitter and receiver subsystems of the transceiver, consumes time and requires the use of dedicated external test equipment. In addition, because the resource requirements imposed by factory testing and calibration may be largely independent of the technology to node utilized for transceiver fabrication, those requirements for testing time and test equipment utilization typically do not scale with dimensional reductions, making conventional factory testing and calibration an increasingly significant limitation on production cost-effectiveness.
Thus, there is a need to overcome the drawbacks and deficiencies in the art by providing a self-testing transceiver architecture suitable for implementation as part of a mobile device transceiver.